1. Field of the Invention
The invention relates to an electrophotographic image forming apparatus, a cartridge and a process cartridge.
The electrophotographic image forming apparatus is an apparatus for forming an image on a recording medium (such as recording paper or an OHP sheet) by the use of an electrophotographic image forming process. It includes, for example, an electrophotographic copying machine, an electrophotographic printer, etc.
The cartridge refers to a charging unit, a developing unit and a process cartridge. The charging unit has a charging member for charging an electrophotographic photosensitive member, and is detachably mountable to an electrophotographic image forming apparatus main body. Also, the developing unit has a developing member for developing an electrostatic latent image formed on the electrophotographic photosensitive member, and is detachably mountable to the electrophotographic image forming apparatus main body. Also, the process cartridge refers to at least one of the charging member and the developing member as process means and the electrophotographic photosensitive member integrally made into a cartridge which is made detachably mountable to the electrophotographic image forming apparatus main body.
2. Related Background Art
In an electrophotographic image forming apparatus of a process cartridge type, the mounting and dismounting of the process cartridge with respect to an electrophotographic image forming apparatus main body (hereinafter referred to as the “apparatus main body” can be effected by a user himself without resort to a serviceman. So, the operability of the image forming apparatus could be markedly improved.
In such an electrophotographic image forming apparatus, it is necessary to apply a voltage to a charging member for charging an electrophotographic photosensitive member of the process cartridge, or a developing member or the like for developing an electrostatic latent image formed on the electrophotographic photosensitive member. Also, the giving and receiving of a voltage and a detection signal (output voltage) to and from developer amount detecting means of an electrostatic capacity detecting type or the like of the process cartridge are sometimes effected.
So, when the process cartridge has been mounted to the apparatus main body, it is necessary to effect electrical connection between the process cartridge and the apparatus main body. Therefore, a cartridge electrical contact has heretofore been provided on the frame member of the process cartridge. On the other hand, in the apparatus main body, there is provided a main body electrical contact to be electrically connected to the cartridge electrical contact. As a result, when the process cartridge has been mounted to the apparatus main body, the cartridge electrical contact and the main body electrical contact are connected together. Therefore, a voltage and a signal are given and received between the apparatus main body and the process cartridge.
Now, during the interchange of the process cartridge or when jamming of a recording medium occurs, an operator performs the operation of dismounting and mounting the process cartridge.
When the process cartridge is detached from the apparatus main body, the main body electrical contact member becomes exposed in the apparatus main body. So, the operator may inadvertently touch the contact member. Thereupon, the fat or the like of his hand may adhere to the contact member, and this has led to the possibility that the reliability of electrical connection is spoiled.
In order to protect such a contact member, there has been proposed a construction in which a protective plate provided in the apparatus main body is moved in operative association with the operation of dismounting and mounting the process cartridge to thereby open and close a contact window (Japanese Patent Application Laid-Open No. 7-77921).